Spinneret



Patented Nov. 8, 1938 UNITED STATES PATENT OFFICE SPINNERET Reginald V.'Williams, Bufialo,'N. Y., and Edward R. McKee, Hermitage, Tenn, assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Original application December 20,

1933, Serial No. 703,244. Divided and this applicationluly 21, 1937, Serial No. 154,931

' 2 Claims. (01. 1s-s) More particularly the invention relates to nozzles useful in the manufacture of products from viscose. In particular the invention comprehends an alloy having qualities which make it of superior value in the manufacture of artificial thread. The invention will be described in connection with the spinneret used for the extrusion of viscose into a coagulating bath in the manufacture of the artificial silk called rayon, but it is to be understood that the invention can be used in any process wherein an extrusion nozzle is subjected to similar corrosive action.

In the manufacture of artificial thread by the viscose process, a viscose solution is extruded through a cup-shaped nozzle, about one-half inch in diameter, pierced with a number of orifices having a diameter of about .003 or .004 inch. The spinneret is subjected simultaneously to hydraulic pressure; to the chemical action of the basic viscose solution containing in the neigh- 25 borhocd of 6% sodium hydroxide; and to the chemical action of the acid coagulating bath containing from about 10% to about 80% sulfuric acid. If a thread of high quality is to be produced, it is essential that all the orifices of 30 the spinneret shall retain their original size and shape, and that the spinneret shall be able to resist for long periods both the mechanical and the chemical forces which tend to aifect it. This is more readily comprehended when it is pointed out that the cost of the spinneret is high. Any tendency on the part of the solution to enlarge the spinneret orifices, or to weaken the spinneret by corrosion, is costly. Furthermore, to prevent the orifices of the spinneret from becoming clogged, the spinneret material must not tend to gather foreign material by adherence or otherwise, and must be capable of mechanical working to produce a thin-walled nozzle having minute orifices.

Heretofore spinnerets have been made of glass, of metals, and of metal alloys. For instance, there have been used alloys of gold and palladium; gold and platinum; palladium, gold, and platinum; and alloys of these metals with small 50 amounts of the baser magnesium, chromium, molybdenum, and nickel. Attempts have been made to form spinnerets from pure platinum, but have not been completely successful because platinum is comparatively soft, too ductile, too malleable, and being difiicult to work, is not adapted to the making of smooth orifices of uni- .form diameter. On the other hand, the comparatively low-platinum, high-gold alloys are more ,readily attacked and are subject to undesirably frequent replacement. 5

An object of this invention is to provide a nozzle which is substantially immune to the combined action of the viscose solution and the coagulating bath, and which is hard enough to be readily worked and to withstand the physical strains to which it is subjected. Other objects of the invention are to improve the uniformity of manufacture of cellulosic pellicles and filaments.

The objects of the invention are accomplished, generally speaking, by means of an extrusion nozzle composed of an alloy of platinum with rhodium, in which the platinum forms at least 90% of the weight of the nozzle, and in which the rhodium forms at least 1% of the weight of the nozzle. The objects of the invention are preferably attained by the use of a platinum-rhodium alloy containing 90% platinum and 10% rhodium.

In the practice of this invention the alloys are prepared in a manner which will be understood by persons skilled in metallurgy. For instance, the proper quantities of the selected metals may be heated in a crucible to a temperature sufficiently high to secure fusion of the metals. The alloy is then cast in molten form into a suitable mold, is cooled, and rolled into sheets which are subsequently stamped in appropriate dies into the shape of the spinneret. Thereafter the orifices are made in the spinneret in any satisfactory manner known to those skilled in the art.

The composition of the alloy should be at least 90% platinum and at least 1% rhodium. A specific alloy which has been found to be of especial value contains 90% platinum and 10% rhodium. This alloy has shown unusual resistance to corrosion and erosion, satisfactory malleability and ductility, no tendency to collect deposits of foreign matter during spinning, and especially long life.

We are aware that certain spinnerets used in the prior art have contained traces of palladium, gold, or rhodium in amounts up to about .l% or .2% but these small quantities serve no useful purpose, the properties of the spinneret being substantially those of the other metals, those prior art compositions being in no sense the equivalent of our alloys.

This invention has been described in connection with spinnerets in the manufacture of artificial thread but it is equally applicable to the manufacture of nozzles useful for casting cellulosic sheets or tubes. The alloys are also useful for the manufacture of the apparatus used'in other processes of regenerated cellulose manu-- facture, for instance, the cuprammonium process.

spinnerets in accordance with this invention exhibit greatly improved results over those hitherto known. This is particularly true in the spinning of fine denier yarn, such as yarn of 1-.

denier per filament. With prior spinneretsjthe enormously high number of spinneret changes made the cost of producing such yarn entirely too high for economical production, and the yarn was not of good quality because of broken filaments, etc. With the present spinnerets, these difficulties have been largely overcome and satis- I the type described by the Draeper patent showed.

deposition of materials in the orifices after a spinning period of 24 hours, some of these depositions being sufiiciently extensive to seriously impair the quality of the yarn produced. With spinnerets comprising platinum and 10% rhodium, on the other hand after a period over twice as long, only 13.4% of the holes in the deposits being sufliciently extensive to seriously impair the qualityof the yarn produced.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments thereof except as defined in the appended claims.

Weclaim: I

1. A spinneret for the production of rayon from viscose, comprising at least 90% platinum and at least 1% rhodium.

spinnerets contained these deposits, none of the i 10 2..A spinneret for the production of rayon from viscose, comprising 90% platinum and 10% rhodium. REGINALD V. WILLIAMS.

EDWARD R. McKEE. 

